Validating CRM 4.0 Customizations Files

When you try to upload a customizations file (xml or zipped) into CRM 4.0 RTM and get the message: "Either the file couldn't be uploaded or this is not a valid customizations file" the first thing that you should try is validating the file yourself using a simple xml tool. I recommend you xml notepad.  Once you open your xml file with xml notepad you just have to go to "View>Schemas" and point to the following 3 files (do a quick search under your CRM Web folder): customizations.xsd, isv.config.xsd, and sitemaptype.xsd. Any errors with the schema should be easily identifiable and, in msot cases, very easy to fix manually.

For deeper troubleshooting, dev errors and trace files are the best alternatives. The "Maintaining and Operating Guide" included as part of the implementation guide has more details.  

You may be wondering, why all the complication? CRM should be telling me exactly what went wrong right from within the UI... I fully agree with you. We did a bunch of enhancement around import/export of customizations but that was one that we missed; partly because, in theory, nobody should have invalid xml files...in practice, it may happen for various reasons (e.g. including manually manipulating the file in unsupported ways).

Well, I hope this helps you troubleshoot any issues with import/export faster.